Punch



(No Modei.

L. PIPER.

PUNCH.

No. 425 456- Patented Apr. 15, 1890.

5 Mama J w 6/WL0M27C' moro-urm., wasumm'nu, n. c.

UNITED STATES PATENT OFFICE.

LUTHER PIPER, OF BERLIN, OONNEOTIGUT.

PUNCH.

SPECIFICATION forming part of Letters Patent No. 425,456, dated April 15, 1890.

v Application filed October 21, 1889. Serial No. 327,736. (No model.)

To all whom it may concern.-

Be it known that I, LUTHER PIPER, of Berlin, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Punches, of which the following is a full, clear, and exact description, whereby any one skilled in the art can make and use the same.

My improvement relates to the class of punches that are used for making rivet-holes and bolt-holes in sheets or plates of metal that are of considerable thickness, and my object is to overcome the several defects that are present in prior punches and limit their d urability.

My invention consists in a punch having a working-face formed with a radial lip and a shearing-edge starting from the working-face diametrically opposite the lip and running out at the base of the lip, as more particularly hereinafter described, and pointed out in the claim.

Referring to the drawings, Figure 1 is a side view of the end of a punch. Fig. 2 is a plan View of the end of a punch. Fig. 3 is a side View of the punch, showing the end of the lip. Fig. f is a side View from a point diametrically opposite the lip.

In the accompanying drawings, the letter n. denotes a punch, made of steel or like metal and of proper quality and diameter for the purpose in hand. A conical projection is located in the center of the working end of the punch, extends beyond the working-face, and forms the center point I), the extreme point being in the axial center of the punch. A lip (Z is formed on the working-face c of the punch and extends from the central point I) to the outer edge of the punch, this outer face being located in a plane substantially at right angles to the axis of the punch.

The edge a of the working-surface of the punch, at a point diametrically opposite the lip, is substantially on a level with the bottom surface of the lip, and from this central line it is cut away on an inclined or spiral line both ways from the center in a curved plane that runs into the base of the lip, and thus relieves it. It is important to the presence of my improvement in a punch that this lip shall be radial that is, located upon one side only of the center point-and that the working-surface of the end of the punch diametrically opposite the lip shall be so located as to encounter the work at substantially the same time that the bottom surface of the lip encounters it. p

In the operation of the punch the center point is located in the guide-hole formed by aprick-punch in the ordinary manner, and while the work is held in place the lengthwise movement of the punch forces the latter into and through the work, the under surface of the lip entering the metal and displacing it at the same time that the shearing action about the circumference of the hole, due to the angular location of the curved workingsurface of the punch, that sweeps spirally backward from a line passing through the point e and the lip d to the base of the lip, is begun. This peculiar conformation of the working-face of the end of the punch centers the punch in the work and makesa shearing cut, that facilitates the operation withoutsubjecting the working-face to undue strains, that splinter and break the punches of the prior art after a comparatively short time.

I have found by experiment that a punch of the prior art most nearly resembling my within -described invention breaks down after punching fifty holes, while a punch embodying my improvement can be used in perfectcondition after punching ten times the same number of holes under the same relative circumstances, thus showing the advantage of the peculiar conformation, as the punch is made from precisely the same stock and material. V

I claim as my invention- As an improved article of manufacture, a punch having a working-surface with a center point and a radial lip on one side only of the center point and a shearin -edge that starts from the working-face in the plane of and diametrically opposite to the lip, extending on both sides of the center and running out at the base of the lip, all substantially as described.

LUTHER PIPER. WVitne-sses:

ARTHUR B. J ENKINS, H. E. BACHARACH. 

